Electron discharge device and associated cavity resonator



Aug. 29, 1950 s. NERGAARD ELECTRON DISCHARGE DEVICE AND ASSOCIATEDCAVITY RESONATOR Filed Jan. 24, 1945 km mm mf j m. L

Patented Aug. 29, 1950 ELECTRON DISCHARGE DEVICE AND ASSO- CIATED CAVITYRESONATQR Leon S. Nergaard, Princeton, N. 5., assignor to RadioCorporation of America, a corporation of Delaware Application January24, 1945, Serial No. 574,283

18 Claims.

My invention relates to electron discharge devices and associatedcircuits and more particularly to cavity resonator circuits suitable foruse with such electron discharge devices.

It is frequently necessary to use cylindrical cavities which can betuned over a small range. The tuning is usually accomplished bycollapsing the cavity axially to vary its volume. This entails a changein spacing between the end plates of the cavity. If the circuit isinternal to an electron discharge device associated with a resonator orforms part of the envelope of the device, this change in spacing alsochanges the interelectrode spacings. If the cavity is exterior to thetube, the change in spacing necessitates moving connections to the tube,which is undesirable if, as is frequently the case, these connectionsalso serve as sup-ports for the electron discharge device.

It is an object of my invention to provide a cavity resonatorparticularly suitable for use with an electron discharge device andwhich may be conveniently tuned.

Another object of my invention is to provide a cavity resonator whichdoes not require changing electrode spacings of the electron dischargedevice in tuning the resonator.

A still further object of my invention is to provide such a resonatorwhich eliminates the need for moving connections, particularly wherethese connections serve as supports for the electron :1

discharge devices.

The novel features which I believe to be characteristic of invention areset forth with particularly in the appended claims, but the inventionitself will best be understood by reference to the following descriptiontaken in connection with the accompanying drawing in which Figure 1 is alongitudinal section of a cavity resonator illustrating the principlesof my invention, Figure 2 is a transverse section taken along the line22 of Figure 1, Figure 3 shows an electron discharge device of thetriode type utilizing input and output cavity resonators and utilizingmy invention, Figure 4. is a top view of the structure shown in Figure3, and Figure 5 is a longitudinal section of an electron dischargedevice and resonator and showing a modification of a resonator madeaccording to my invention.

In Figure l is disclosed a resonator of the type under discussion andillustrates the principles involved.

This resonator comprises the hollow drumshaped member iii having flatend walls and a tubular outer or side wall and having within it thecentral cylindrical conducting member ll surrounded by the coaxialtubular collar l2. Positioned and extending between the collar I2 andthe inside Wall of the hollow member lll is an annular tuning ring ismovable axially of the resonator by means of rod it provided with handleM.

In effect the arrangement shown in Figures 1 and 2 comprises a pair ofconcentric annular resonators coupled together by the space between theinner end of collar l2 and the opposite end of the resonator. The innerresonator has the outer radius a, inner radius 0 and the axial length 3and contributes inductance L,=2s log, x 1w henry The outer resonator hasan outer radius 22, inner radius a, and variable axial length y. Itcontributes an inductance L =2y log, 3X 10' henry Hence, the totalinductance is equal to L=2 E 10 %+y 10 i0- henry The range of variationis governed by the range of y. The range may also be controlled byvarying the length of sleeve of radius a, and also by varying radius a.

In Figure 3 is shown an ultra high frequency oscillator in which thecavity resonator connected to the output of the tube incorporates theinvention described above. In this arrangement I em.- ploy a triode ofthe type described in my copending application, Serial No. 516,388 filedDecember 31, 1943, now Patent No. 2,461,125, dated February 8, 1949, andassigned tothe same assignee as the present application. It comprises acathode assembly 28 and an oppositely disposed anode 2! with anintermediate grid having a ring seal 22 extending through the envelopecomprising the insulating portions 23 and 23, preferably of glass.

The cathode conductor and cathode heater leads comprise the outertubular conductor 211 and the inner conductor 2 and the input cavityresonator is coupled between the cathode and the grid ring and includesthe inner tubular member 25 and outer tubular member 2?, which togetherwith shorting ring 28 form a coaxial line cavity resonator. The outertubular conductor 20 connected to the cathode is capacity coupled asshown to the inner tubular member 26. The 1 c n uctor 24, is connectedto the cathode 3 heater and to lead 25, and the lead is connected toconductor 20. These leads serve as the cathode heater leads and as thecathode lead. Tuning is accomplished by means of the tuning handle 29connected to the tuning shorting ring 28.

The output cavity resonator employing my invention is in the form of ahollow drum and includes the plate-like end wall member 30, an annularwall member 3| and top plate end wall, member 32 insulated from wallmember 3! by means of the insulating ring 33, preferably of mica. Theanode 2! is provided with a coupling flange 2! clamped to the'wallmember 32 by means of the clamp 36. Within the resonator is a collarelement 35, and between the collar element and the wall member 3| ismovably mounted a tunable shorting ring 35 operated by means of handle3?. As described above this resonator may be tuned to vary its resonantfrequency by moving the ring 38.

A variation of the arrangement shown in Figures 3 and a is shown inFigure 5. Here the two communicating portions of the cavity resonatorare formed by means of sylphon bellows 4c and 40' within the tubularwall 3! and having different diameters and connected by the conductingring 41 cooperating with adjusting screws 42 and {53. By operation ofthese adjusting screws the different diameter portions may besimultaneously adjusted in relative axial length by moving the ring 4!axially within the resonator, to vary the resonant frequency of theresonator. The smaller bellows 40 corresponds to the tubular collars l2and 35 of Figs. 1 and 3 wherein the axial length of the collar isadjustable.

Thus with the arrangement described above I accomplish all the purposesset forth above and. provide a triode amplifier or oscillator which maybe tuned over a comparatively wide range.

While I have indicated the preferred embodiments of my invention ofwhich I am now aware and have also indicated only one specificapplication for which my invention may be employed, it will be apparentthat my invention is by no means limited to the exact forms illustratedor the use indicated, but that many variations may be made in theparticular structure used and the purpose for which it is employedwithout departing from the scope of my invention as set forth in theappended claims.

What I claim as new is:

- 1. An electron discharge device having a cathode, grid and an anode, acoaxial line resonator coupled between said grid and said cathode, andmeans extending between the walls of said resonator for tuning saidresonator, and a drumshaped second resonator coupled between said gridand anode and having a surface of revolution and having wall portions ofdifferent diameter surrounding a portion of said electron dischargedevice, the ends of said electron discharge device extending beyond theends of said drumshaped resonator, and movable means contacting thewalls of said second resonator for varying the effective axial length ofone of said wall portions to vary the resonant frequency of said sec-0nd resonator, both of said wall portions of said second resonator beingspaced laterally from said electron discharge device.

2. An electron discharge device having a cathode, grid and an anode, acoaxial line resonator coupled between said grid and said cathode, and adrum-shaped second resonator coupled between said grid and anode andhaving a surface of revolution and having wall portions of differentdiameter surrounding a portion of said electron discharge device, theends of said electron discharge device extending beyond the ends of saidsecond resonator, and movable means contacting the walls of said secondresonator for varying the relative effective axial lengths of said wallportions to vary the resonant frequency of said second resonator, bothof said wall portions of said second resonator bein spaced laterallyfrom said electron discharge device.

3. An electron discharge device havin a cathode, grid and anode, acoaxial line resonator coupled between said grid and said cathode, and asecond resonator coupled between said grid and anode, said second cavityresonator including a drum-shaped hollow member surrounding saidelectron discharge device and having within it a collar member coaxialwith the axis of revolution of said drum-shaped member and extendingfrom one end thereof and positioned between and spaced from the electrondischarge device and the outer wall of said second cavity resonator, anda ring element extending between said collar member and the insidesurface of said drum-shaped member and movable axially to vary theresonant frequency of said second cavity resonator.

4. An electron discharge device having a cathode, grid and anode, acoaxial line resonator coupled between said grid and said cathode, meanswithin said resonator for tuning said resonator, and a second cavityresonator coupled between said grid and anode, said second cavityresonator including a drum-shaped hollow member having within it acollar member coaxial with the axis of revolution of said drum-shapedmember and extending from one end thereof and spaced from said electiondischarge device, and a tuning ring extending between said collar memberand the inside surface of said drum member and movable axially to varythe resonant frequency of said second cavity resonator.

5. An electron discharge device having a cathode, grid and an anode, acoaxial line resonator coupled between said grid and said cathode, and asecond resonator coupled between said grid and anode, the outer wall ofsaid second resonator including two connected bellows of differentdiameter, andmeans for varying the relative lengths of said bellows.

6. An electron discharge device having a cathode, grid and an anode, acoaxial line resonator coupled between said grid and said cathode, and asecond resonator coupled between said grid and anode, said secondresonator including a bellows of conducting material having portions atdifferent diameters, a fixed ring, a first portion of one diametercoupled to said ring and a second portion of another diameter coupled tothe opposite side of said ring, and means for fixing the ends of saidportions opposite the ends fixed to said ring, and means for moving saidring to vary the relative lengths of the portions of differentdiameters.

'7. A cavity resonator including a substantially drum-shaped hollowmember having end walls, a tubular member extending from the innersurface of one of said end walls into said hollow member and coaxialwith the axis of rotation of said drum-shaped member, and movable meansextending between said tubular member and the inside surface of the wallof said hollow member surrounding said tubular member whereby the spacewithin said hollow member opening into the interior of said tubularmember may be varied to vary the resonant frequency of said resonator.

8. A cavity resonator including a substantially drum-shaped hollowmember having end walls, a tubular member extending from the innersurface of one of said end walls into said hollow member but spaced fromthe other end wall of said hollow member, and an annular conductingmember extending between said tubular member and the wall of said hollowmember surrounding said tubular member and movable for varying the outerspace within said hollow member which opens into the interior of saidtubular member to vary the resonant frequency of said resonator.

9. A cavity resonator comprising a drumshaped member having end walls,a, tubular member within said drum-shaped member coaxial with the axisof rotation of said drum-shaped member and supported from one of saidend walls and extending axially of and within said drumshaped member butspaced from the other end wall of said drum-shaped member, and aconductor extending along the axis of rotation and coaxial with saidtubular member and extending beyond the free end of said tubular member,a ring element mounted in the space between the inner surface of thewall of the drum-shaped member surrounding said tubular wall and thetubular wall and movable longitudinally of the drum-shaped member tovary the frequency of said resonator.

10. An electron discharge device having a grid and an anode, and adrum-shaped cavity resonator surrounding said grid and said anode, saidr resonator comprising a pair of end walls each connected for highfrequency currents to one of said grid and said anode, an outer tubularwall connecting the outer edges of said end walls, an

inner tubular wall extending axially from one of said end walls towardbut spaced from the other end wall and positioned between and spacedfrom said outer wall and said device, said resonator walls providing twocommunicating resonator portions, and axially-movable means extendingbetween said inner and outer tubular walls for varying the axial lengthof one of said resonator portions to vary the resonant frequency of saidresonator.

11. An electron discharge device having a cathode, grid and anode, and adrum-shaped cavity resonator surroundin said grid and said anode, saidresonator comprising a pair of end. walls each connected for highfrequency currents to one of said grid and said anode, said grid and theend wall coupled to said grid shielding said cathode from said anode, anouter tubular wall connecting the outer edges of said end walls, aninner tubular wall extending axially from one of said end walls towardbut spaced from the other end wall and positioned between and spacedfrom said outer wall and said device and providing two communicatingcavity resonator portions, and axially-movable means extending betweensaid tubular walls for varyin the axial length of one of said resonatorportions to vary the resonant frequency of said resonator.

12. A cavity resonator comprising a substantially drum-shaped conductinmember having end walls, a tubular outer wall, a tubular partitionextending coaxially from one of said end walls into said hollow membertoward but spaced from the other end wall and providing two concentriccommunicating annular cavity resonator portions of diiTerent outerdiameters, and axially- 6 movable means extending between said tubularmember and said outer wall, whereby the volume of at least one of saidresonator portions may be varied to vary the resonant frequency of saidresonator.

13. A cavity resonator including a substantially drum-shaped hollowmember having end walls and a tubular outer wall, at least one of saidend walls having an axial aperture adapted to receive an electrondischarge device therein, a tubular member extending from the innersurface of said apertured end wall into said hollow member andpositioned between and spaced from said aperture and said outer wall andcoaxial therewith, and axially-movable means extending between saidtubular member and said outer wall whereby the space within said hollowmember may be varied to vary the resonant frequency of said resonator.

14. A cavity resonator including a substantially drum-shaped hollowmember having end walls and a tubular outer wall, at least one of saidend walls having an axial aperture adapted to receive an electrondischarge device therein, a tubular member extending from the innersurface of said apertured end wall into said hollow member but out ofcontact with the other end wall and positioned between and spaced fromsaid aperture and said outer wall and coaxial therewith, andaxially-movable means extendin between said tubular member and saidouter wall whereby the space within. said hollow member may be varied tovary the resonant frequency of said resonator.

15. A cavity resonator including a substantially drum-shaped hollowmember having end walls and a tubular outer wall, each of said end wallshaving an axial aperture adapted to receive an electron discharge devicetherein, a tubular member extending from the inner surface of one ofsaid end walls into said hollow member and positioned between and spacedfrom. said outer wall and the aperture in said one end wall and coaxialtherewith, and axially-movable means extending between said tubularmember and said outer wall whereby the space within said hollow membermay be varied to vary the resonant frequency of said resonator.

16. A cavity resonator including a substantially drum-shaped hollowmember having end walls and a tubular outer wall, each of said end wallshaving an axial aperture adapted to receive an electron discharge devicetherein, a tubular member extending from the inner surface of one ofsaid end walls into said hollow member but out of contact with the otherend wall and positioned between and spaced from the outer wall and theaperture in said one end wall and coaxial therewith, and axially-movablemeans extending between said tubular member and said outer Wall wherebythe space within said hollow member may be varied to vary the resonantfrequency of said resonator.

17. A cavity resonator including a substantially drum-shaped hollowmember having end walls and a tubular outer wall, a tubular bellowsextending coaxially from one of said end walls into said hollow member,and movable means attached to the free end of said bellows and extendingbetween said bellows and said outer wall, whereby the space within saidhollow member may be varied to vary the resonant frequency of saidresonator.

18. A cavity resonator including a substantially drum-shaped hollowmember having end walls, a pair of tubular bellows of difierent diameter7 extending coaxially from opposite end walls into said hollow member,and movable means connecting the free ends of said bellows, whereby thespace within said hollow member may be varied to vary the resonantfrequency of said resonator.

LEON S. NERGAARD.

REFERENCES CITED Number 8 UNITED STATES PATENTS Name Date DallenbachJuly 25, 1939 Llewellyn Feb. 20, 1940 Linder Feb. 25, 1941 GoldstineFeb, 29, 1944 McArthur July 18, 1944 Haefl. May 21, 1946 Wagner July 16,1946 Gurewitsch Oct. 8, 1946 Gurewitseh Nov. 19, 1946 Gurewitsch June22, 1948

